Passenger transport vehicles, such as commercial aircraft (and especially aircraft with low cabin altitude) experience humidity and other moisture-laden conditions. This can particularly be the case for aircraft that operate in high humidity environments and/or aircraft that employ humidification systems at various locations on-board the vehicle. As such, aircraft (and other vehicles) can have “rain in the plane,” which is a condition that occurs when excess water accumulates on insulation blankets or other equipment in the bilge or belly of the aircraft or vehicle. In many instances, this can lead to saturated insulation blankets and excessive operational weight.
The “excess” water that creates this problem may be from any number of sources. For example, it may the result of passenger's exhaling normal breaths, humidification systems, condensation, ovens, coffee makers, ambient humidity (e.g., on ground), or any other cause.
Various attempted solutions at managing increased humidity as it condenses on the cold structure of the aircraft (and the resulting “rain in the plane”) have generally involved low tech solutions such as using wicking material in strategic places and providing revised drain paths to cause the water to move efficiently from the cabin of the aircraft to the bilge. For example, one solution has been to position spring-loaded drain valves in the belly of an aircraft. The valves open when the aircraft lands to remove moisture or water that may have collected during flight. Another solution has been to line the belly with insulation blankets that absorb collected moisture and water (but that need to be removed and dried.) More effective solutions are desired.